ALL | Answer | No answer | p Value | ||||
---|---|---|---|---|---|---|---|
N | Per cent | N | Per cent | N | Per cent | ||
Number of systematic reviews | 118 | 100 | 80 | 68 | 38 | 32 | |
Search of unpublished trials and/or test for publication bias | 0.914 | ||||||
Publication bias discussed only or not mentioned | 39 | 33 | 26 | 33 | 13 | 34 | |
Unpublished trials searched OR publication bias tested | 56 | 47 | 39 | 49 | 17 | 45 | |
Unpublished trials searched AND publication bias tested | 23 | 19 | 15 | 19 | 8 | 21 | |
Contact with authors of the studies | 0.427 | ||||||
Study authors not contacted | 45 | 38 | 28 | 35 | 17 | 45 | |
Study authors contacted for method or unspecified reason | 15 | 13 | 12 | 15 | 3 | 8 | |
Study authors contacted for unreported outcomes | 58 | 49 | 40 | 50 | 18 | 47 | |
Duplicate publications | 0.057 | ||||||
Not searched or not mentioned | 37 | 31 | 21 | 26 | 16 | 42 | |
Searched and found, not referenced OR no mention of results | 71 | 60 | 54 | 68 | 17 | 45 | |
Searched, found and referenced | 10 | 8 | 5 | 6 | 5 | 13 | |
Sponsors of the studies | 0.809 | ||||||
Not mentioned | 91 | 77 | 63 | 79 | 28 | 74 | |
Information extracted | 21 | 18 | 13 | 16 | 8 | 21 | |
Information extracted and subgroup analyses performed | 6 | 5 | 4 | 5 | 2 | 5 | |
Conflicts of interests of study authors | 0.703 | ||||||
Not mentioned | 113 | 96 | 77 | 96 | 36 | 95 | |
Information extracted | 5 | 4 | 3 | 4 | 2 | 5 | |
Information extracted and subgroup analyses performed | 0 | 0 | 0 | 0 | 0 | 0 | |
Ethical approval of included studies | 0.481 | ||||||
Not mentioned | 115 | 97 | 77 | 96 | 38 | 100 | |
Information extracted | 3 | 3 | 3 | 4 | 0 | 0 | |
Information extracted and subgroup analyses performed | 0 | 0 | 0 | 0 | 0 | 0 | |
Number of procedures applied | 0.403 | ||||||
None | 11 | 9 | 6 | 8 | 5 | 13 | |
1 or 2 procedures | 48 | 41 | 34 | 43 | 14 | 37 | |
3 or 4 procedures | 56 | 47 | 38 | 48 | 18 | 47 | |
5 procedures | 3 | 3 | 2 | 3 | 1 | 3 | |
Median (IQR) | 2.5 (1–3) | 2.5 (2–3) | 2.5 (1–3) | ||||
Explicit mention of misconduct by reviewers | 0.296 | ||||||
No, or not mentioned | 111 | 94 | 74 | 93 | 37 | 97 | |
Yes | 7 | 6 | 6 | 8 | 1 | 3 |
Answer: reviews in which extracted data were confirmed by reviewers. No answer: reviews in which extracted data were not confirmed by reviewers. p Value testing the null hypothesis of equal distribution between the reviews for which the authors responded to our inquiry and those who did not (χ2 test). Percentages may not add-up to 100% because of rounding errors.